Oil circuit breaker



Sept. 8, 1931.

s. T. SCHOFIELD OIL CIRCUIT BREAKER Filed Aug. 9, 1927 x I I x l I INVENTOR Skml'y Tchcf//d ATT'ORNEY Patented Sept. 8, 1931 ATENT OFFICE STANLEY T. SCHOFIELD, OF XVILKIBTSB'URG, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC 86 IrIANUFACTURIL'G VANIA COMPANY, A CCRPOBATION OF PENNSYL- OIL CIBCUIT BREAKEB Application filed August 9, 1927.

My invention relates to circuit-interrupting devices and more particularly to devices that may be employed to dissipate the stored energy of solenoids.

One object of my invention is to prov de a circuit interrupter with means 'for dissipating the stored energy of the inductive circuit when the latter is open-circuited and to thereby prevent the inductive surge from travers ing the supply circuit.

Another object of my invention is to provide a circuit-interrupting device with means for producing an are to complete a circuit for dissipating the inductive energy in a circuit.

A still further object of my invention is to provide a circuit-interrupting device with a double-break contact, one pair of separable Contacts of which is employed 'for establishing an arc to short-circuit the inductance, while the other pair interrupts the current supply to a solenoid.

Trouble has been experienced in the past, when employing heavy-current solenoids for the operation of circuit interrupters and other devices, by reason of the fact that surges Were produced in the supply circuit when the solenoid was disconnected there'from. The surge produced thereby on traversing the said supply circuit would burn' out ground detectors and cause breakdowns in the insulation of other apparatus. Besistors eniployed to shunt across the solenoid to eliminate this transient voltage proved unsatisfactory, as the energy in the solenoid was not dissipated soon enough and the solenod functioned to delay the opening of the circuit interrupter.

My invention consists in completing` a circuit across the terminals of the solenoid by means of an arc which dissipates the energy in a very short time and eliminates transient voltages in the supply circuit.

My invention will best be understood by referring to the drawings, in which Figur-e 1 is a View, partly in elevaton and partly in section, of a particular embodiment of my invention.

Fig. 2 is a plane View thereo'f.

Fig. 3 is a diagram showing the connec- Serial No. 211,(349.

tions of the various circuits of the particular embodiment of my invention shown in Figs. 1 and 2.

My invention comprises, in general, a contactor i that may be of any standard type having bridgin member for opening the circuit oi 'the solenoid at two points, one contact co-operating with an auxiliary terinal to short-circuit the solenoid in a mann ore fully described hereinafter, while ,he other contact insures the opening of the ply circuit.

Fig. l shows an arc chute 2 with the conventional arc-splitter, of 'the prior art, removed and an arc horn 3 of conducting mate-g rial provided in its stead. An end 4 of the arcing horn is adjacent to the path of the are which forms upon the movement of a contact member 5 to its open position. When the contactor l is operated, an arc is first' produced between Contacts 5 and 6 and is then e caused to transfer to a path between the end 4: of the arcing horn 3 and the statonary contact member 6. A pair of contact members 7 in an adjacent arc chute 8 may be provided and connected in series with the Contacts 5 and 6 by means OI" a conducting shunt 9.

Beferrin: to the circuit connections as shown in Fig. 3, a solenod 11 isthe operating means for a circuit interrupter 12. One: terminal of solenoid 11 is in circuit with the s'tationary contact member 6, the other terminal being connected to one side of a supply line and also to the arcing horn 3. The contacts 7 are connected in series with the other side of 'the supply line. By the closing of a control switch 13 in said supply line, the solenoid 14 is energized and closes the contactor 1. Thereupon the shunt 9 completcs the circuit to the coil ll from the supply line' through Contacts 5, 6 and 7 and the circuit interrupter 12 closes.

Vhen the control switch 13 is opened, the contactor-closing coil 14 is deenergized, and the eontactor l opens, thus separating the contacts 7 in the arc chute 8 and the Contacts 5 and 6 in the are chute 2. Upon the opening of the separable contacts 5 and 6, the arc drawn thereby will be transferred from the contact 5 to the end 4: of the arcing horn 3,

establishing an are between the end 4 and stationary contact 6 to complete the circuit across the solenoid 11. This permits the magnetic energy stored in the solenoid to be quickly dissipated in the are thus established. By reason of Contacts 7 being open the further flow of current from source 13 to solenoid 11 is prevented, regardless of the existence of arcs in arc chute 2.

It will thus be seen that I have provided a method of dissipating the energy in a highlyinduetive circuit very quickly, at the same time preventing transient volta ne from traversing the supplycircuit thereby nrotecting lamps and instruments connected ther-eto from being burned out or having their insulation destroyed.

It is to be understood that such chan es in the form arranqement and connection of the comnonent narts of mv invention may be made as shall fall within the scope of the annended claims.

I claim as my invention:

1. In combination with an inductancer a device for disconnecting said inductance from its source of supplyr arcin r means nositioned adjacent to a contact of said device and means for shuntinq the inductance including the arcing means.

2. In comhination with inductance a source of voltaqe for energizinsr said inductance. means for connecting and disconnecting said inductznce from said source and means for establishinq an are in shunt with the inductance when said disconnectinsx means is onerated.

3. The method of dissinating the electromagnetic energy of :n inductance which comm'ises disconnecting: said inductance from the source sunnlvingr current thereto and estab- 'lishin' an are in Shunt to said nductance.

4. The eomhination with an inductance. of a pair of senarable contact-s for disconnechne one end of said inductance from the current source sunplvinsr it. and means for transferring one terminal of the arc incident to serarating said contacts to the other end of said inductance.

5. In combination with a solenoid. a circuit-onening device therefor comnrising a nair of sebarable Contacts. a source of voltage for enerqizing the solenoi d controlled by the said device and an arcing horn in proximity to the said contacts and in eircuit with the solenoid.

6. In combination with a solenoid. a circuit-opening device therefor comprisine a pair of stationary contacts and a bridging member, a source of Voltage for energizing the solenoid through the said Contacts and bridging member, and an arcing horn. in proximity to one of the said stationary contact members and in circuit with the said solenoid.

7. In combination with a solenoid in circuit with a source of energy controlled by a circuit-interrupting device, a second circuit adapted to include the solenoid, and arcing means for shunting the solenoid to complete the said second circuit when said circuit-interrupting device is opened.

8. The combination with a motor for operating a mechanism, of a circuit for supplying energy thereto, a switch for said circuit having a pair of contact members that are bridged by a conducting member for drawing two arcs in series relation when interrupting` the circuit to the motor, a contact member positioned adjacent to the are path of one of said eres, a circuit from said motor to the last said contact member that is completed when an arc impinges on said contact member, the other are, upon extinguishnent, disconnecting the source of energy from said motor.

In testimony whereof, I have hereunto subscribed my name this 3rd day of August,

STANLEY T. SCHOFIELD. 

